1. Field of the Invention
The present invention relates to a system for detecting a position of a device such as a capsule endoscope, which is swallowed and passes naturally through the digestive tract of the subject, by a position transducer that is disposed on the outside of the subject and obtains information of the position of the device in the subject.
2. Description of the Related Art
In recent years, in the field of endoscopes, a swallowable capsule endoscope has been proposed. The capsule endoscope has an image capturing function and a radio communication function. The capsule endoscope has the function of traveling in the body cavity, for example, in the organs such as the stomach and the small intestine with peristalsis of the organs and sequentially capturing images for a period of time since the capsule endoscope is swallowed from the mouth of a subject for inspection (examination) until it is naturally excreted.
Image data captured in the body by the capsule endoscope as the capsule endoscope travels in the body cavity is sequentially transmitted by radio communication to the outside and stored into a memory provided on the outside. The subject can freely move throughout the period after he/she swallows the capsule endoscope until it is excreted by carrying a receiver having a radio communication function and a storing function. After the capsule endoscope is excreted, a doctor or nurse can display the images of the organs on a display based on the image data stored in the memory and make a check.
A capsule endoscope has been proposed in which the receiver has the function of detecting the position of the capsule endoscope in the subject to capture, for example, an endoscope image of a specific organ in the subject. As an example of a capsule endoscope system having the position detecting function, a capsule endoscope system using the radio communication function provided in the capsule endoscope is known. Specifically, the system has a configuration that a receiver provided on the outside of a subject has a plurality of antenna elements, and has the function of receiving a radio signal transmitted from the capsule endoscope by the plurality of antenna elements and, based on intensities received by the antenna elements, detecting the position of the capsule endoscope in the subject (see Japanese Patent Application Laid-open No. 2003-19111, for example).